Vibrating screen with one or more groups of screening elements

ABSTRACT

A vibrating screen comprises a main frame and at least two parallel pluralities of separate screening members. The members of each plurality feed one to another in cascade and each of the members is separately resiliently mounted on the main frame for independent vibrating movement relative to the main frame and relative to each other. Vibrating means and motor means for driving the vibrating means are provided for the screening members.

[ Feb. 15, 1972 United States Patent Venanzetti Peterson.... .........,...209/366.5 X Ranger ...,...209/326 Walters..........................,.......209/3 l 3 307 675 999 111 Ill 74 720 327 769 907 332 [54] VIBRATING SCREEN WITH ONE OR MORE GROUPS OF SCREENING ELEMENTS FOREIGN PATENTS OR APPLICATIONS 868,547 l/1953 Germany.....,......................209/366.5

Primary Examiner-Frank W. Luttcr Assistant Examiner william Cuchlinski, J r. A!l0rney-Young & Thompson Appl. No.: 829,166

[30] Foreign Application Priority Data June 6, 1968 [57] ABSTRACT A vibrating screen comprises a main frame and at least two Italy.............. ...|741s A/68 parallel pluralities of separate screening members. The members of each plurality feed one to another in cascade and each of the members is separately resiliently mounted on the main frame for independent vibrating movement relative to the 58 5 O EO M13 a n 2 1 ,m3 M1 3 0 "3 2 1 4 1 W MR 0 "9B W 9 "20 m m m mm L MI 0 W d S M UmF ll] 2 8 555 Ill [56] Reierences Cited main frame and relative to each other. Vibrating means and UNITED STATES PATENTS motor means for driving the vibrating means are provided for the screening members.

209/314 1 Claim, 4 Drawing Figures 2,115,110 4/1938 2,775,347 12/1956 Weston.........

PATENTEDFEB 15 I972 3.642.133

SHEET 1 0F 2 INVENTOR M/CHEL 5 yz-wzm/zfrr/ BY 7* JM/ ATTORNEYS PATENTEDFEB 15 I972 3.642.133

sum 2 OF 2 INVENTOR 44/0/1545 Mow/v25 rr/ BY W v WW ATTORNEYS The object of the present invention is the provision of a vibrating screen including one or more groups of screening elements.

It is known that in vibrating screens the following two parameters are of fundamental importance: the frequency of oscillation and the amplitude of the oscillation. If the screens are of fine mesh, then the frequency must be high and the amplitude low.

For instance, in order to screen powdered products with 1 mm. openings, the corresponding frequency may be 3,000 impulses/minute with an amplitude of approximately l.52mm., while for screening a product with openings of mm., the frequency may be 1,000 impulses/minute with an amplitude of 10-12 mm.

It is clear that, the screening capacity of a screen being dependent on its dimensions, for determining the product quantities to be screened, the resulting dimensions, would be quite difficult to attain for high-frequency operation; this above all because the rolling elements (roller bearings) have, as is well known, speed and lift limits.

The present invention has the purpose of overcoming the mentioned limitations with the screens of known type.

The present invention relates to a vibrating screen, characterized in that it includes on a main frame one or more screening groups (mounted in parallel to each other in case of more than one group) each group being formed by screening elements mounted in series, each element being in condition to vibrate in autonomous manner in respect to the said frame, on which it is elastically mounted.

The single screening elements are therefore of small dimensions and limited weight, so as to allow operation at high frequencies, while leaving unaltered the indispensable characteristics of extreme stiffness and resistance to stress.

The annexed drawings represent in a schematic form two embodiments of the vibrating screen according to the present invention:

FIG. I is a side view of a vibrating screen with a fixed main frame.

FIG. 2 represents the same vibrating screen in a plan view.

FIG. 3 is a side view of a vibrating screen with oscillating main frame.

FIG. 4 is a front view of the vibrating screen according to FIG. 3.

With particular reference to the embodiment of FIGS. 1 and 2, the vibrating screen, according to this invention, includes a rigid main frame 1 which is stationary in respect to support structure 2; two groups of screening elements are also provided, those of the first group being shown at 3 and those of the second group at 4.

When the groups are two or more, they are mounted in parallel, as can be seen in FIG. 2. Each group, for instance, that including the screening elements 3, has its elements disposed in series and each one vibrates in autonomous manner in relation to frame 1, on which it is elastically supported, for instance, through springs 5.

The screen comprises also a feed hopper 6 and a chute 7 for the screened material.

Frame 1 has a steep inclination in order to permit, due to the gravity, the passage of the material from one element to the other and, at last, remaining material will be discharged through well-known exit opening 8.

Each screening element 3 or 4 is composed of a screen and of a peripheral frame to which are fixed springs ends 5, whose other ends are fixed to said frame 1.

Each screening element 3 or 4 is partially superimposed with its exit aperture 3a (or 411) over the following screening element. This permits the passage of the material to be screened from one screening element to the other as above described.

In this manner is effected the total and absolute separation between the material passing through the screen and that remaining on the screen.

Each screening element 3 or 4 rs drrven by an eccentric mass vibrator 9.

The vibrators are driven by an electrical motor or by a group of electrical motors, singly or in groups, namely through pulleys 11 and belts 12.

Said transmissions are in gear ratio in order to obtain the desired frequency for the movement of the various screening elements 3 or 4. In the case of plural groups of parallelmounted screening elements, as for example in FIG. 2, it is possible to provide joints 13 connecting the vibrators acting on the elements 3 and those acting on elements 4 disposed substantially on the same transverse axis in respect to the assembly.

By means of the transmissions, it is also possible to render, in compliance with requirements, the vibration frequency of any screening element 3 and 4 of a group equal to or greater or less than that of the next element. This is very important, considering that the frequency varies in accordance with the physical and chemical characteristics of the product to be screened.

The vibrating screen can also include other parts, well known, but not represented in the drawing, adapted to vary automatically and/or cyclically the established frequencies for the various screening elements.

Considering now the embodiment represented in FIGS. 3 and 4, the vibrating screen includes a main frame 22 oscillating at a predetermined frequency, obtained for instance, through the unidirectional vibrator 23, driven by motors 24 and 25 through belt and pulley transmissions or through a rotary vibrator of the type employed on inclined vibrating screens. In the example of the drawing, the frame 22 can oscillate in respect to the supports 16 and 17, thanks to interposed elastic elements.

On frame 22 screening elements 18 are mounted as described in connection with screening elements 3 and 4 of the first embodiment.

Otherwise, the embodiment of FIGS. 3 and 4 is like that of FIGS. 1 and 2, with the exception that in this second case the passage of the material to be screened from a screening element 18 to the following screening element is not realized by gravity alone but by means of the oscillation of frame 22 or by the combined action of gravity and the oscillation of a frame like frame 22.

From the preceding description it is evident that, the vibrating screen, according to the invention, offers all the advantages cited in the introduction of the specification and reduces remarkably the limitations of the vibrating screens of the known types.

Therefore, it is a substantial improvement in this field.

Modifications and variations are possible to the described screen without departing from the scope of this invention.

What is claimed is:

l. A vibrating screen comprising a main frame, at least two parallel pluralities of separate screening members, the members of each plurality feeding one to another in cascade in each longitudinal plurality, separate means resiliently mounting each of said members on the main frame for independent vibrating movement of each of said members relative to said main frame and relative to each other, vibrator means con nected to each of said screening members, and motor means for driving said vibrator means. 

1. A vibrating screen comprising a main frame, at least two parallel pluralities of separate screening members, the members of each plurality feeding one to another in cascade in each longitudinal plurality, separate means resiliently mounting each of said members on the main frame for independent vibrating movement of each of said members relative to said main frame and relative to eAch other, vibrator means connected to each of said screening members, and motor means for driving said vibrator means. 